Subsurface pump



July 14, 1964 R. L. ANDERSON ETAL SUBSURFACE PUMP Filed Dec. 3, 1962 lA/l/E/V TORS ROBERT L. ANDERSON and JOHN M. ROHR/G By )6 Attorney United States Patent 3,140,667 SUBSURFACE PUMP Robert L. Anderson and John M. Rohrig, Huntington Beach, Calif., assignors to United States Steel Corporation, a corporation of New Jersey Filed Dec. 3, 1962, Ser. No. 241,886 3 Claims. (Cl. 103-489) This invention relates to an improved subsurface pump particularly for handling heavy viscous oils or for use in slanted wells.

In some oil wells there is a substantial resistance to downward movement of the rod string during a downstroke of the pump. As a result, the pump plunger may not travel downwardly as rapidly as the drive at the surface is operating. The length of the pump stroke at the bottom of the well is diminished with loss of efficiency. The rod string must sustain a high compressive load during each downstroke, resulting in severe stresses therein. This condition may arise, for example, in wells which produce heavy viscous oils or in slanted wells where rod friction is high.

An object of the present invention is to provide an improved subsurface pump which overcomes the foregoing difliculties and assures that the rod string is properly tensioned during a downstroke.

A further object is to provide an improved subsurface pump which embodies two barrels and two plungers of similar cross section arranged to load the upper plunger with the weight of the fluid column in the well, thereby assuring that the rod string always is under tension.

In the drawing:

The single figure is a diagrammatic vertical section of a subsurface pump constructed in accordance with our invention.

Our pump comprises stationary upper and lower barrels and 12 of similar cross section joined end to end. We attach the upper barrel 10 to the lower end of a conventional well tubing 13. We mount spaced apart upper and lower reciprocable plungers 14 and 15 of similar cross section in the upper and lower barrels respectively. A tube 16 is rigidly attached at opposite ends to the two plungers. Between the two barrels we fix an annular packing assembly 17 which closely receives the outside of tube 16. The packing assembly divides the space within the barrels outside the tube into an upper chamber 18 and a lower chamber 19. The upper and lower plungers 14 and 15 have bores 20 and 21 which form continuations of the bore through tube 16, thus providing a vertical passage which extends the length of the plungers and tube. We attach the upper end of the upper plunger 14 to the lower end of a conventional rod string 22 through a connector 23. The passage through the plungers 14 and 15 and tube 16 contains spaced apart upper and lower valves 24 and 25. The tube has ports 26 which lead to chamber 19 and always remain below the packing assembly 17 as the plungers travel up and down. The connector 23 has ports 27 which furnish communication between bore 20 and tubing 13. The upper barrel has breather ports 28 leading from chamber 18. The lower end of the lower barrel 12 is open (no standing valve).

In operation, a drive mechanism at the surface (not shown) alternately lowers and raises the rod string 22, plungers 14 and 15 and tube 16. As the plungers make a downstroke, the weight of the fluid column in tubing 13 bears against the upper plunger 14 and against the upper 3,140,667 Patented July 14, 1964 valve 24. This weight forces the plungers downwardly and thus maintains the rod string under tension. The weight also holds valve 24 closed. Valve 25 opens and admits well fluid into the bore of tube 16 and thence through ports 26 into chamber 19. As the plungers make an upstroke, valve 24 opens and valve 25 closes. The lower plunger 15 forces fluid from chamber 19 through ports 26, tube 16 and ports 27 into tubing 13 and thence to the surface.

From the foregoing description it is seen that our invention affords a subsurface pump mechanism of simple construction which effectively maintains the rod string under tension at all times. Thus the rod string is not subject to undue stresses, and the efficiency is improved.

While we have shown and described only a single embodiment of the invention, it is apparent that modifications may arise. Therefore, we do not wish to be limited to the disclosure set forth but only by the scope of the appended claims.

We claim:

1. A subsurface pump comprising upper and lower barrels of similar cross section joined end to end, upper and lower plungers of similar cross section mounted for reciprocable movement in the respective barrels, a tube attached at opposite ends to said plungers, a packing assembly fixed within said barrels between said plungers and closely receiving said tube, said plungers and tube providing a passage extending the length thereof, spaced apart upper and lower valves mounted in said passage, and means for attaching a rod string to said upper plunger, said tube having a port located between said valves and leading to said lower barrel said packing assembly, Whereby said upper plunger and upper valve are subject to the full weight of a fluid column in a well to maintain the rod string under tension.

2. A subsurface pump comprising upper and lower barrels of similar cross section joined end to end and adapted to be attached to the lower end of a well tubing, upper and lower plungers of similar cross section mounted for reciprocable movement in the respective barrels, a tube attached at opposite ends to said plungers, a packing assembly fixed within said barrels and dividing the interior of the barrels into upper and lower chambers, said packing assembly being located between said plungers and closely receiving said tube, said plungers and tube providing a passage extending the length thereof, spaced apart upper and lower valves mounted in said passage, and means for attaching a rod string to said upper plunger, said tube having a port located between said upper and lower valves and communicating with said lower chamber, said port remaining below said packing assembly as the plungers and tube reciprocate in the barrels, whereby said upper plunger and valve are subject to the full weight of the fluid column in the tubing to maintain the rod string under tension.

3. A pump as defined in claim 2 in which said upper barrel has a vent port communicating with said upper chamber, said attaching means has a port providing communication between said passage and the well tubing, and the lower end of said lower barrel is open.

Martin Sept. 21, 1954 King Jan. 2, 1962 

1. A SUBSURFACE PUMP COMPRISING UPPER AND LOWER BARRELS OF SIMILAR CROSS SECTION JOINED END TO END, UPPER AND LOWER PLUNGERS OF SIMILAR CROSS SECTION MOUNTED FOR RECIPROCABLE MOVEMENT IN THE RESPECTIVE BARRELS, A TUBE ATTACHED AT OPPOSITE ENDS TO SAID PLUNGERS, A PACKING ASSEMBLY FIXED WITHIN SAID BARRELS BETWEEN SAID PLUNGERS AND CLOSELY RECEIVING SAID TUBE, SAID PLUNGERS AND TUBE PROVIDING A PASSAGE EXTENDING THE LENGTH THEREOF, SPACED APART UPPER AND LOWER VALVES MOUNTED IN SAID PASSAGE, AND MEANS FOR ATTACHING A ROD STRING TO SAID UPPER PLUNGER, SAID TUBE HAVING A PORT LOCATED BETWEEN SAID VALVES AND LEADING TO SAID LOWER BARREL SAID PACKING ASSEMBLY, WHEREBY SAID UPPER PLUNGER AND UPPER VALVE ARE SUBJECT TO THE FULL WEIGHT OF A FLUID COLUMN IN A WELL TO MAINTAIN THE ROD STRING UNDER TENSION. 